MONDAY, May 2, 2016 (HealthDay News) -- Small children riding in taxis often aren't in a car safety seat, putting them at risk for injury and death in an accident, U.S. researchers warn.

All 50 states require young children to be in car safety seats when traveling in a motor vehicle. But, many municipalities exempt taxis from this safety rule, the researchers said.

Study senior investigator Dr. Ruth Milanaik is with Cohen Children's Medical Center in New Hyde Park, N.Y. "Given that car safety seats have been shown to significantly decrease the risk of death or injury from motor vehicle collisions, there should be no exemptions in car seat safety laws for taxi services. When it comes to child safety, even one preventable injury calls for a change in policy," she said said in an American Academy of Pediatrics (AAP) news release.

The researchers monitored places in New York City such as airports, train stations, shopping malls and tourist locations and observed 69 taxis picking up or dropping off passengers. More than 100 children were among those passengers. Only 11 percent of small children -- no taller than the taxi's side view mirror -- were properly restrained while in the taxi. And, almost all of the children in that group were secured in an infant carrier, according to the researchers.

The researchers also called 97 taxi companies in the New York City area. Almost four out of 10 said they had car safety seats available. Of those companies, 18 percent said they had a limited number of seats or that a reservation was required for a seat. Only 8 percent charged extra for a seat, the researchers said.

Health code restrictions and allergy and hygiene concerns were some of the reasons cited by taxi companies for not having child safety seats available, the researchers noted.

Motor vehicle accidents are a leading cause of death among children in the United States. There's a 70 percent increased risk of death or injury for 7- and 8-year-olds who aren't properly restrained in vehicles, the researchers said.

Infants and toddlers should be secured in rear-facing child safety seats. Children should continue to be placed in car safety seats or belt-positioning booster seats until they reach the height of 4 feet, 9 inches, the AAP advises.

The study was to be presented Sunday at the Pediatric Academic Societies annual meeting, in Baltimore. Findings presented at meeting are generally viewed as preliminary until published in a peer-reviewed journal.